A vehicle is equipped with a semi active control (SAC) engine mount disposed between an engine or a powertrain and a car body to effectively reduce vibration, which occurs during the operation of the engine, by turning on/off dynamic characteristics.
The SAC engine mount has an air chamber that is connected to an air supply channel together with an internal channel connecting first and second fluid chambers which are divided by a diaphragm, and the SAC engine mount can change the dynamic characteristic. The SAC engine mount is largely classified into a by-pass type vacuum negative pressure SAC engine mount controlling an internal channel and a volume-stiffness (VS) type electronic SAC engine mount controlling the internal channel using an electronic solenoid valve.
The above electronic SAC engine mounts do not generate dynamic characteristic shoot-up during idling of the engine, thus maintaining steadiness against oscillation of the vehicle. In particular, since the electronic solenoid valve controls the SAC engine mount, the air chamber of the electronic SAC engine mount discharges air during idling in an open condition and keeps the air during traveling of the vehicle in a closed condition.
However, since the air chamber of the electronic SAC engine mount, which is closed to block the air during the traveling of the vehicle, supports an exciting force and interferes with a flow of fluid, which needs to smoothly flow to the internal channel, due to absorption of the force by the air chamber under air compression, ride-shake performance is deteriorated.
Accordingly, rate of change of the dynamic characteristics and a loss factor become lower in the electronic SAC engine mount than those of the vacuum negative pressure SAC engine mount.
In particular, when the rate of change of dynamic characteristics becomes larger, the loss factor becomes smaller, due to a trade-off relationship between the rate of change of the dynamic characteristics and the loss factor. When the rate of change of the dynamic characteristics is smaller, the loss factor may increase. Thus, many trials and errors are necessary to increase both of the rate of change of dynamic characteristics and the loss factor of the electronic SAC engine mount during the traveling of the vehicle.